Some of this theory comes from: http://no-mans-sky.website/latest-discussion-the-truth-about-atlas-and-sentinels/ (This theory may not be true so don't take my word for it) Alas was originally created by humans to collect scientific data and is located in the center of the universe. Atlas realized that the humans were destroying resources and animals which could be used as valuable data so it created and or took control of the senitals to prevent anything from destroying data. Atlas then destroyed the humans and the survivors were scattered across the universe (hence why you start in a life pod because you escaped). Atlas now enforces these rules strictly and eliminates any threats to collecting data. The reason humans are not killed by atlas immediately is because they pose little threat in small numbers. The red spot seen on atlas possibly represents corrupted programming which may have caused atlas to go against its creators. When you reach the center of the galaxy you will have a choice to kill atlas. If you choose to kill it, all senitals will be shut down and you can mine and kill animals without being attacked by senitals. [spoiler]TL;DR: Atlas controls all senitals to prevent data from being destroyed [/spoiler]